Wireless networking systems are well known and include, among many others:                i. WiFi or 802.11a and 802.11b systems, described in IEEE Std. 802.11, IEEE Standard for Information Technology—LAN/MAN—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, IEEE, 1999; IEEE Std 802.11A-1999, Information Technology—Telecommunications and Information Exchange Between Systems—LAN/MAN—Specific Requirements, IEEE, 1999; and IEEE Std. 802.11B-1999, IEEE Local and Metropolitan area networks—Specific requirements—Path 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher Speed Physical Layer (PHY) Extensions in the 2.4 Ghz band, IEEE, 1999.        ii. WiMAX or 802.16d/802.16e systems, described in IEEE Std. 802.16-2004, IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems, IEEE, 2004; IEEE Draft standard 802.16e/D6, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, IEEE, 2005.                    (referred to herein as 802.16)                        
In general, such systems allow client devices including personal computers, laptop computers, game systems, portable digital assistants (PDAs) and “smart” mobile telephones, among many others, that are equipped with integrated or peripherally connected wireless network adapters, to inter-communicate or to communicate with a central access point or base station without a physical wire. In some protocols such as 802.16, clients may be also be termed subscribers or subscriber stations, but for generality, the term “client” is used herein. Such networks generally use a protocol that operates over a radio frequency channel, termed an airlink. As is well known, applications and higher level protocols may use a Media Access Control (MAC) protocol layer to manage the resources of the airlink and to provide a standard interface to protocol layers or programs executing at a higher level. In general, MAC layer implementations are designed to maximize available bandwidth and to minimize the likelihood of the occurrence of errors in communications over the network. Both the base station and client devices may participate in the execution of the MAC layer protocol and other network protocols to enable the operation of the wireless network. In general, it may be assumed that both a base station and a client have a protocol execution component, which may be a processor, a logic circuit or circuits, or a combination thereof. This protocol execution component may execute a hardwired protocol, or a program embodying a protocol that is stored in a memory or in other storage accessible from the protocol execution component, or both.
Orthogonal Frequency Division Multiple Access (OFDMA) is a well known technique providing improved efficiency in the utilization of the airlink. A MAC layer implementing OFDMA creates virtual two-dimensional regions for data communication along the dimensions of time and channel frequency. Each such region may be termed an airlink frame, or frame for brevity. In OFDMA implemented with time division duplexing, uplink frames and downlink frames are separated in time; in OFDMA implemented with frequency division duplexing, uplink and downlink frames occupy separate frequency channels at the same time. A MAC layer implementation may allocate regions of the airlink frame, or regions, to specific clients and reserve a region defined by a sub-channel and time-slot for communications from or to a specific client. This may be done either statically or dynamically depending on the rate of change of position of the clients relative to the base station, the bandwidth requirements of clients, co-interference between clients, and other factors.
Some wireless networking systems such as 802.16 based systems may implement Space Division Multiple Access (SDMA) in conjunction with OFDMA. In SDMA networks, advanced antenna systems (AAS) on the base station and clients allow for multiple, non-interfering communications on the same frequency region of the airframe in the same time slot. A MAC layer implementing OFDMA with SDMA may be thought of as organizing the airlink in three dimensions, with multiple two dimensional OFDMA regions available for each independent space division. Thus two different clients of an SDMA network may communicate with the base station using regions of the airlink frame that are overlapped in terms of both frequency and time.